Rudimentary forms of endless, flexible devices to transmit rotational power, or torque, between two shafts have been employed for centuries. For example, a form of "chain" drive comprising wooden struts held in the desired position by cable, or line, much like a rope ladder, was used more than 3000 years ago. The rope ladder configuration was supplanted by metallic chains during medieval times, but it was not until the nineteenth century that vast technical strides were made in the development of efficient, flexible power transmission systems.
One avenue of that development provided considerable advances toward perfection of the currently well known chain drives.
Another avenue of that development lead to the current state of the art relating to belt drives, and the present invention constitutes a novel and unique improvement to the belt drive art. In a belt drive the power is transmitted between the drive and driven shafts by the frictional engagement between the pulleys, one on the drive shaft and one on the driven shaft, and the endless, flexible belt. In time, the historically employed flat belt was replaced, for many applications, by the far more efficient, and reliable, V-belt.
A wide variety of materials were employed in the manufacture of belt drives. Initially, leather was one of the prime materials from which the belts were fabricated. Cotton webbing has also been extensively used to make belts, as has rubber and even flexible steel bands. Even in this current age of high technology a combination of fabric and vulcanized rubber comprises a highly popular construction for V-belts. However, that construction will not suit all installations.
Many considerations are taken into account when selecting the material to be used in the manufacture of V-belts, not the least of which are the environmental conditions to which the V-belt will be subjected. Other considerations are the magnitude of the power to be transmitted as well as the rotational speed of the shafts and the resulting linear speed to which the V-belt will be subjected.
By and large V-belts have historically been fabricated as single units that are intended to transmit power under the application of forces that induce a tensile stress in the V-belt. However, the manufacture of V-belts as a single unit has at least one serious limitation inasmuch as a single, localized defect, occurring either as a result of some flaw introduced during the manufacturing process or as a result of wear occasioned by usage, requires the replacement of the entire V-belt. As such, it is recognized that V-belts can be more efficiently fabricated from a plurality of individual elements, or links. Thus, if one link in a V-belt should be defective, or otherwise require replacement, replacement can be effected without the necessity of replacing the entire V-belt.
A common approach has been to fabricate the individual links with a T-shaped connector at one end thereof and with a notch, or slot, at the other end that has a configuration specifically adapted to receive the T-shaped connector presented from an identically shaped, successively located link. While this specific approach cures the major defects experienced with one piece V-belts, it subjects the user to its own unique problems. The chief disadvantage is that when such links are assembled in an endless belt they tend to become disengaged from one another at inopportune times, thus resulting in considerable inconvenience to the user. As might be expected, this disadvantage has spawned a variety of improvements targeted to obviate that difficulty.
Another disadvantage of the prior known link arrangements resides in the fact that the configuration of the notch, or slot, tends to reduce the transverse columnar strength of each link, thus subjecting the interconnection between successive links to potential binding as a result of the transverse loading applied against the conjoined links as a result of their engagement with the sheaves on the drive, and driven, shafts, respectively. The very fact that the T-shaped connectors are disposed longitudinally beyond the body portion of the prior known link constructions in order to facilitate their engagement with the notch, or slot, on the successive link precludes the T-shaped connector from enhancing the transverse columnar strength of the prior known link arrangement.
A further disadvantage attendant upon having the T-shaped connector extend longitudinally beyond the body portion of the link is that the joinder between the T-shaped connector and the body portion of the link is virtually non resistant to the application of torsional forces between successive links.
Perhaps the most representative configuration for links employed to form V-belts adapted to transmit power by loads resulting in tensile stress within the V-belt is disclosed in U.S. Pat. No. 4,473,365.
It should also be appreciated that whereas the various and sundry readily replaceable link arrangements utilized to form V-belts effect power transference when the V-belt is under tensile stress, certain well known V-belt arrangements exist that are uniquely suited to the transmission of power by the application of forces resulting in compressive stresses within the V-belt. Such arrangements employ one or more flexible, metal bands, or strips, which extend along the path defined by the belt and which support a plurality of compressive members that are disposed along the complete length of the bands.
Perhaps the most representative configurations for this style of belt are disclosed in two U.S. Pat. Nos. 3,720,113 and 4,080,841.